In the manufacture of some types of rigid pin-populated printed wiring boards, terminal pins are inserted into apertures of the boards and electrically engage portions of printed wiring on the boards to provide for connections to external circuits. Typically, the spacing between adjacent apertures on each board is extremely small. For example, the spacing between apertures on one board is 0.125 inch. Further, each terminal pin typically has a square cross section of, for example, 0.025 inch except in those areas where the pin is formed with lateral ears having a push shoulder and an aperture-engaging portion intermediate the ends thereof. The pin is relatively slender and typically measures one and one-half inches in length.
In assembling the pin within an aperture of a board, the end of the pin which is closest to the aperture-engaging portion is inserted into the aperture. A pushing force is then applied to the push shoulder of the pin to urge the aperture-engaging portion into the aperture whereby the pin is frictionally retained with the board.
Due to close spacing between apertures and the small size of the pin, it is most difficult and tedious to assemble the pins on an individual basis. Additionally, the relatively small size and slenderness of the pins necessitates delicate handling during insertion of the pins into the apertures. However, where each board may contain thousands of closely-spaced apertures, efficiency and economy dictate that the pins be prealigned and gang-inserted into the board apertures.
In the past, many techniques have been developed for assembling pins or terminals with a supporting structure. For example, in one technique, a supporting structure containing apertures is placed in a generally horizontal plane within a vibratory device. A plurality of individual slender pins are deposited on top of the supporting structure which is then vibrated. The pins are then vibratorily directed into the apertures. The vibratory technique requires that the pins be separated from each other before being deposited onto the supporting structure and that they be generally slender without any unbalancing structure such as lateral ears. Examples of the vibratory technique are illustrated in U.S. Pat. Nos. 3,667,103 and 3,812,569.
In another technique, the pins are stamped in a linked configuration having an edge-strip carrier. The pins are then fed into an insertion machine in the linked configuration and are separated individually from the carrier. Each of the separated pins are fed individually and independently of the other separated pins through feed chutes and assembled with a supporting structure. Examples of this technique are illustrated in U.S. Pat. Nos. 2,814,802; 2,970,370; 3,067,902; 3,566,464; and 3,867,760.
In a similar technique, strip-carried pins or terminals are separated one at a time from the linked assembly and assembled with a supporting structure. Examples of this technique are illustrated in U.S. Pat. Nos. 3,711,922 and 3,867,760.
Another technique provides for the simultaneous assembly of pins with a supporting structure as the pins are held in a linked comb-like arrangement by a carrier strip. After assembly of the pins with the structure, the strip is separated from the pins. Examples of this technique are illustrated in U.S. Pat. Nos.
3,676,926; 3,769,679; 3,875,636; and 3,946,477.
In a variation of the strip-held insertion technique, just noted above, a plurality of rows of pins are linked in an end-to-end configuration with laterally aligned pins of the rows forming sets of pins. Lateral linking strips define each set of pins. The leading set of pins with the lateral linking strip is separated from the trailing sets and assembled with a bobbin. After the bobbin and assembled pins are processed through several pin-staking steps, the lateral linking strip is separated. This technique is illustrated in U.S. Pat. No. 3,562,903.
In still another technique illustrated in U.S. Pat. No. 3,545,606, individual pins are assembled in a precise arrangement with a carrier pad. The pins are inserted into apertures of a supporting structure and the carrier pad is removed.
U.S. Pat. Nos. 2,871,551 and 2,947,965 illustrate an assembly of pins linked by carrier strips. Although not illustrated, it is generally noted that strip carried pins of this type can be fed into automatic machines for assembly of the pins with supporting structures. However, neither of these patents suggest specific techniques for such assembly of the pins with the supporting structures.
In another technique disclosed in U.S. Pat. No. 3,550,250, a plurality of pins are formed in a parallel spaced arrangement with a carrier strip and an anti-distortion strip extending along opposite ends of the pins to form a linked assembly. The pins are formed in sets of three each with the outer pins of each set being identical and the center pin being dissimilar. The set of pins of the linked assembly are advanced into an apparatus whereat the anti-distortion strip is removed from the leading set of three pins. Thereafter, an intermediate portion of the center pin of the leading set is clamped and the center pin is then separated from the carrier strip while the two outer pins of the set are retained with the carrier strip. A prepositioned bobbin is then moved to insert relatively the three pins into apertures of the bobbin. The carrier strip, which remains linked to the two outer pins of the leading set and all other pins of the trailing sets, is then utilized to advance the bobbin through a series of stations whereat various operations are performed. Therefore, this technique teaches initially clamping a single pin of a set of strip-held pins, then separating only the single clamped pin from the strip, inserting the clamped pin and the strip-held pins into a bobbin and utilizing the strip to transport the pin-bobbin assembly. Further, use of the strip to transport the pin-bobbin assembly tends to place stresses on the inserted pins which are still retained with the strip. This is particularly critical when the pins are slender.
In still another technique illustrated in U.S. Pat. No.
3,641,646, three independent rows of end-to-end linked pins are fed into a machine and the leading pin of each row is initially clamped while the pins are separated from the trailing pins. The clamped pins are then inserted into a bobbin. It is noted that the three pins are not initially linked together in any way and thereby do not contain a carrier strip. Thus any alignment necessary for insertion must depend on the manner of feeding the individual rows of pins into the machine.